Mantle cell lymphoma are positive for all of the following except
**Core Concept**
Mantle cell lymphoma (MCL) is a rare and aggressive type of B-cell non-Hodgkin lymphoma characterized by the overexpression of cyclin D1 protein due to the t(11;14) translocation. This genetic abnormality leads to the dysregulation of cell cycle progression, resulting in uncontrolled cell proliferation.
**Why the Correct Answer is Right**
MCL cells typically express a distinct immunophenotype, including positivity for cyclin D1, CD5, and CD20. The cyclin D1 protein is a key regulator of the cell cycle, and its overexpression in MCL cells is a hallmark of this disease. The CD5 antigen is also commonly expressed on MCL cells, which helps to distinguish them from other types of B-cell lymphomas.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect - Mantle cell lymphoma cells are typically positive for CD20, a B-cell surface antigen.
**Option B:** Incorrect - Cyclin D1 overexpression is a characteristic feature of mantle cell lymphoma, making this option incorrect.
**Option C:** Incorrect - CD5 is commonly expressed on mantle cell lymphoma cells, making this option incorrect.
**Clinical Pearl / High-Yield Fact**
Mantle cell lymphoma is often associated with a poor prognosis, but treatment outcomes have improved with the use of novel therapies such as ibrutinib and lenalidomide.
**Correct Answer:** D.